You were the Kageyama's first child, even before Shigeo.
You were a esper too, and you and Shigeo helped each other when you were starting to control your powers. This made the two of you closer, and since Ritsu discovered his powers later in his teens, he felt a bit left out. The age difference didn't help either: You were in your third year of high school, you were always busy with it and whenever you could rest you were with friends. Ritsu felt bad about it.
"Hey..." Ritsu knocked on your bedroom door, and since it was already open, he went in. But he stopped at the door, however, since he didn't feel close enough to go in yet. "I was wondering, do you have some time this weekend for us to do something together? Whenever we go out, Shigeo goes along, but I've seen just you two going out several times. I wanted to do something with you and me. Can we?"
Ritsu was actually willing to have a close relationship with you, just like he had with Shigeo! Would you cooperate?